Liquid micrometer-indicator.



T. S. BO0TH..

uoum MICROMETER INDICATOR.

APPLICATION FILED MAR.2, I917.

Patented Nov. 6, 1917.

In "L THOMAS SMITH BOOTH, OF NEW HAVEN, CONNECTICUT.

LTQUID MICROEETER-IKDICATOR.

' Specification of Letters Patent.

Patented Nov. 6, 1917.

Application filed March 2, 1917. Serial No. 151,911.

To all whom it may concern:

Be it known that I, THOMAS S. BOOTH, a citizen of the United States, residing at New Haven, in the county of New Haven and State of Connecticut, have invented a newa gage in determining variations of surfaces, the object of the invention being to provide an accurate gage with means for adjusting it to varying temperatures; and the invention consists in the construction hereinafter described and particularly recited in the claims. I

In carrying out my -invention, I employ a glass tube 3 having a longitudinal passa e 4 the upper part 5 of which is of smaller iameter than the lower part 6 into which it merges by a taper, and the lower .endcurves into the edge of the tube ,to. form a flaring mouth 7. The upper end is closed by a head- 30, preferably of metal, formed with a valve-chamber 8 in which is a valve 9 formed with a stem 10 extending through a perforation 11 in the head. The head is also formed with a vent 12 above the valve and with a filling opening 13 which, is closed by a screw plug 14. Connected with the lower end of the tube and completing the mouth 7, is a ring 15 which. is mounted in a cylinder 16. In this cylinder is a piston 17 mounted upon the upper end of a spindle 18 which extends downward through the cylinder 16, and entering this.

cylinder and extending into the path of the piston 17 is an adjusting screw 19. -The upper face of the piston is concaved and the edge accurately fits the inner walls of the cylinder. The space between the upper face of the piston and the mouth of the tube 3 forms a chamber 20 which is filled with mercury or other suitable liquid which extends up into the tube 3., The chamber formed by the flaring mouth'at the bottom of the tube and the concave face of the piston, facilitates the introduction'of the li uid and prevents the formation of'air cells. he lower part 6 of the tube is graduated from zero up, and the upper portlon 5 is graduated from zero up, and preferably partly inclosed by a protecting shell 21 ofmmetal. Around the spindle 18 and tending to push the piston 17 upward is a coil spr1ng22 of suitable tension to counterbalance the weight of the.piston and the liquid resting upon it. The cylinder 16 may be mounted in a bracket 23 having a downwardly extending arm 24 on which is pivoted a bell-crank lever 25, one arm 26 bearingagainst the lower end of the spindle 18, and the other end 27 adapted to bear upon the work. Preparatory to using this gage for work not requiring the closest measurement, the adjustin screw 19 will be turned to force the piston 1 upward, .or allow it'to move downward until the top of the column of mercury registers with the zero mark 28 on the lower part of the tube 3. A slight upward movement of the spindle 18 will force the liquid into the tube and the extent of movement of the column of liquid will be greatly in excess of the extent of "movement of the spindle so that slight movement of the spindle will register on the gage so as to be readily readable by the operator. -For use in connection with work requiring very close measurement, the screw 19 will be adjusted to cause the top. of the column of liquid to register with the zero mark 29 on the upper part of the tube, and

movement of the spindle will then register onthe upper part, of the tube which having ment of the spindle and the' variation will be more readily perceived. As the column of liquid rises in the tube, the air above it will pass the valve 9 and escape through the vent 12. Should the device be inverted or the liquid rise to the top of the tubeflahe valve 9 prevent the escape a smaller diameter will cause the liquid to 7 move to a greater extent for thesame movewardly extending spindle, and an adjustable stop mounted in the cylinder behind the piston and projecting into the path of the piston and having a bearing thereon for adjusting the piston to cause the liquid in said chamber to register at zero.

2. A micrometer indicator for test gages, comprising a glass tube provided with a scale and formed at its lower end with a flaring mouth, a head at the upper end of said tube, said head formed with a vent, a valve formed with a stem extending into said vent and adapted to close said vent, a cylinder in which the lower end of the tube is mounted,

a piston in said cylinder forming with said tending to force the piston upward, and a body of liquid above said piston.

In testimony whereof, I have signed this specification in the presence of two subscribing witnesses.

THOMAS SMITH BOQTH.

Witnesses:

FREDERIG C. EARLE, MALCOLM P. NICHOLS. 

